Brake



Oct. 15, 1940. K, E LAPWQOD 2,218,201

BRAKE -Filed June 3, 1939 2 Sheets-Sheet l r: .or I back. plate: to..;Which=is-attached :1a-plurality` of Patented Oct. l5, 1946 ionJune d relates. to;l shoe.A brakes foirthe lri'ndvcomprising a'l ixedfsupport rigid-3 :arcuate .-1 ;shoes:; x provided with :1 spreading means whereby.' :the l shoes; `are r`movedVf outwards into; 'contaotrfwithfthe' .internal @surface of'V a; ro,- tating dru1r1'a.When the brake,l is applied;` f

It is'the :.mainrobjectf'of thev preksentvqinvention to.l provide :af4 relatively `simpler construction; of vbrakeirr which each of .the shoesactsiin a `leading sense when the drum is rotated in" its y normal direction `.;.j tif. 3....1n1 15:@ :i

- further objectfofythe-inventionisA `to5provide an improved form of shoe mountngwhioh enables .thev an'choredend .of thetshoelzto .pivot adjusting-'device adaptedxtoztakeiup 'wear-in he 4andalsofislide` .towards and away 'from the-drum, preferably in lthe manner describedand claimed ingcoependingapplication SerialfNO.; r18,0.;362zf11ed on.December.:15,f1937. 1;; 1

Thegivention haswasz-another object the'.;pr0 `visionv ofV .ia- .brake ,which -is particularly eelcient inpperatior r`asV both` of. ,the` shoesi'actfin vaffleading sense inv the normal directionfofdrums-rotation; 'andn4 .which fincorporates:YaV simple storm Tof usualsh'oeflining's.Y i Accordingrito .the invention ga' brake-comprises -ment mounted? upon@ said support, .1anf applying elementv I.alsomounted upon said vsupport aad.-

elements? toftransfer :force inacompressionifrom ljacent .one-end: of. thezbraking: element, ianinter'- :mediate member whichi is z=disposedL between said one to :the: other,` .and iis" connected W-ithmne'element by.;A a J sliding@ joint enabling-j the adjacent irend-f 5f1 the braking ,elementtofmoveitowards and away from the drumpav Second; applying -.'xi1ean's-beingprovided at the r'oppositetend-off'aid .;Inythe rbrake shown in Figures 1v to 3. @the lfixed .Support gcomprises; ag; sheet; Ametal bachi-.plate ffl 0 ranged ff o1; spreading .,giapart'- finto.:.contacta-.Witl1l a 10 rotating drum I3, a pair of rigimareuatebrake shoes lfandzl5:;Thes:shoesglkandgl55a1'e1miaintained in f1 their, p11?livers;relationship; tof. the. back folate .10.;.by5i means.; Qf;.studs1.6@-fwhimextend :fromffsa'id YJoack platethrouha-,slots illifviormed 15 r-in the Websgof the-shoesffwhich:latter zareflene.'

.fgag'ved byf )p vasliers.. Yirparriadj byirthegstuds. awEach shoe fis retrated-byffapair. of coiledf tension .fspriiigsa` s .thesebeing anchored tozfpins .2I1and-.Nieupon'fthelbackffplatenln as shown :f2 They-.construotim he cylindeml laandithe soleiatedsgzpartsz-.wil ybe 'seenamoreclearlyxsin and. --gspectirely.` The pstonffzisgformedawith a. ar dials aneefl:adapted:toalengagewth-ithef nd :iandhatasran abutmentffor oonjunctio'n'- fwith,` tiiefsadI :applying :s .elementz to fenablevit tto# act as an'1'abutme1itfurthe-braking i; elementfy when; the saidrz second@y applying.r-`-mesa.ns

Vas,engaged. y

mediate member 33, this sliding movement being damped frictionally owing to the force exerted by the spring washer 31. It will be noted that the end surface 42 of the shoe I5 is so shaped that the line of sliding when produced passes Vto that side of the axis of the drum' I3 remote from the shoe I5, and the inclination of this direction is preferably arranged in the manner described in co-pending application Serial No. 180,362 filed on December 15, 1937.

The piston 25 is connected with the shoe I4 through the medium of an adjusting device comprising a screw 44 having a slotted head 45 engaging the web of the shoe I4. The screw 44 is fitted with a nut 46 having a radial flange 41 adapted to be urged into contact with the piston "25 by the pull-0E springs I9 and 20. A thin metal shield 48 is interposed between the ange 41 and the piston 25 and slides upon the exterior of the cylinder I I in order to exclude water and dirt, the iiange 41 conveniently being shaped. with teeth so that it can easily be rotated to effect the adjustment of the shoe I4. IIt will be noted that the flange 41 and shield 48 are adapted to engage with the end of the cylinder II, so that when the drum I3 is rotated in a clockwise direction the cylinder II constitutes an abutment or anchorage for 'the shoe I4.

The internal working spaces of the cylinders I I and I2 are connected together by a pipe 50, and both are fed with pressure liquid through a pipe I leading to the cylinder II. If the drum I3 is rotatingin the normal direction shown by the arrow and pressure liquid is fed through the pipe 5I, the pistons 25 and 26 in both cylinders II and I2 will be forced outwardly and will thus spread the shoes I4 and I5 into contact with the drum. The rotation of the latter, however, carries the shoes round in an anti-clockwise direction so that in each case the flange 29 of the piston 26` engages the end of the cylinder and constitutes an abutment for the shoe, both shoes acting in a leading sense and thus producing a large braking force. In moving towards land. away from the drum I3 each of the shoes I4 and I5 normally moves pivotally about the centre of the partspherical recess 3I in the piston 26 but the provision of the sliding surfaces-42 and 43 has the important `eil'ect of enabling the shoe toV accommodate itself to the drum, and thus toe-grab and other forms of erratic action are avoided.

A mechanical operating device is included for use in parking or in emergency, and is of the known form comprising a lever 52` which is pivoted to the top part of the shoe I5 by a bolt 53 and carries a thrust link 54. link is formed with a nger 55 adapted to slide. between a pair of pegs 56 and 51 attached to the shoe I4. When the lower end of the lever 52 is pulled to the left by a tension cable 58, the upper ends of the shoes I4 and. I5 are spread apart into.

contact with the drum I3 by means of the link 54 an'd their lower ends both receive support from the cylinder I2 which serves as ananchorage or abutment in each case. When the drum I3 is rotating in the normal direction the shoe I4 acts in a leading sense, and, due to the provision of the intermediate member 33 at its lowerend. is able to accommodate itself freely to the surface of the drum and thus produce a relatively large ybraking force.. v

In the brake shown in Figures 4 to 6 the back plate I0 is again provided with two shoes M and I5, the upper ends ef which are, however, spread-A apart 'by an actuating means of fa mechanical 'I'he opposite end of this nature. This actuating means comprises a body 60 which is bored at 6I and 62 for the slidable re- .ception of plungers 63'and 64 respectively. The body 60 is also formed with a passageway 65 which extends in a direction at right angles to the plane of the back plate I Il and'which accommodates with considerable lateral play a bifurcated member 66. This member is fitted with a pin 61 which forms the pivot for a pair of sector-shaped members 68 and 69 having curvedv surfaces 10 and 1I arranged to roll upon oblique cam surfaces 12 and 13 respectively upon the plungers 63 and 64. The bifurcated member is operated by a tension rod 14 fitted with a collar 15 adapted to cooperate with a hydraulic piston 16. 'I'he latter is mounted slidably within a cylinder v11 having an inlet connection 18 leading to any convenient source of pressure liquid, so that when the piston 16 is moved a pull is exerted upon the tension rod 14 and the consequent movement of the bifurcated member 66 causes the sector-shaped members 68 and y69 to spread apart the shoes I4 and I5 through the medium of the plungers 63 and 64. 'I'he collar 15 is formed with a tubular extension 19 having a cap 80 cooperating with a head 8I upon the tension rod 8 2 of a mechanical brake' rigging. This rigging is normally connected with the usual hand brake lever (not shown), which latter can thus be used for applying the brake shoes I4 and I5 during parking or in an emergency.

The plunger 64 is as shown in Figure 5 arranged to engage a shoulder' 83- in the body 60 so that it can serve as an abutment or anchorage for the brake shoe I5, said plunger being formed with aV groove 84 having a convex bottom of semicircular shape as indicated at 85 in Figure 4. 'I'his groove is engaged by a correspondingly shaped part of an intermediate member 86, which latter in consequence is capable of moving pivotally about a centre shown at 81. The intermediate member 86 is formed with a lug 34 as in the previous example, this being held in sliding frictional engagement with the web of the brake shoe I5 by means of a pin 36, spring washer 31, plain washer 38 and circlip 39. As before, the end surface 42 of the shoe I5 is arranged to slide against a wall 43 formed upon the intermediate member 86. The surface 42 is again inclined so that the direction of sliding, if produced, would pass to that side of the axis of the brake drum I3 remote from the shoe I5, thepin 36 of course being arranged to pass through a slot 4I formed in the web ofthe shoe l5 and also through a reinforcing plate 40 secured thereto. f

From the cylinder 11 a pipe connection 89 leads to .a motor cylinder 90 secured to the back l -the nut element 95 is provided with a ilange 98 whereby the length of the thrust device 94, 95 can be adjusted during the assembly of the brake. The piston 92 is formed with a spigot 89 which isadapted to engage with a thrust element IIIII extending slidably through the bottom of the cylinder 80,' packing cups IOI and 'III2 being y'fitted to prevent leakage -of liquid. The cylinder 98 is enclosed within a thin metal casstructed similarly tmospheref'ima in ia, plulnger member I 06 iWhich/Sslidesi radially' within the body-SL91; h'efbottoxnof itheislotir-'IUS beingizconvexas'o asiwtolserve.asfa .pivotalimountl ing or'ithei intermediate: memberl A.'1`liefiloody is formedewithrgapainY L a-plurality,.of groovesnI-LS- iormed in AItheMadja-f cent. endoftheplungen lil illes 'Drake vkShoes '11;4 i; and4 1,55' and a the;Iv drums I3 xiis reduced. In order facilitate :thm-adjustment a. diametralridge LI .is-formedaoross-thezend Offthe :mrew l |J-'I,;a ndengagesjinv succession with 5; ;;T11e;;1.10rm21 rlat. i0 thefbrake lustlated-is in yan antij clockiiviseV di ation; and: When'pre'ssuiteliquiddssupplied:through-the.zconneotionim the upper endsjof the brake; shoes L41 ando-'I 5 fare-sboth urged intoQ-contatrwithf the. drumfgl Atfethe. Sametime;therpressure;liquidlventeringrth yl x;- derrf-.urges theloweraend-tof the `asl'ioe i out;-`

Wardly, With't-he resulttthat thegplungenrli -abutsr- Y. Y againstthe shoulder 8;31sani .gbothshoesua v @leading sense; :Eachzfofxsaid shoe moreover "s cloolgwis directionaeftheishoe;i5.;

izo-act; .leading :sense;.1owing toftheyfacteethat? the otationcauses the spigotymponffthef piston 19 zainfgthe smotonrcylinder; to f.' 'engage 'tv-ith the thrust Aelement ill, the plunger 1xwbleizog forcedV outwardly fbyf it Shapeimembeme whenetneitensionrod rigging ffsoiilsed; te appl hee-corresponding sectorwilliheappreciatedxhat epa n fro n, 1 unioni-said? compression from one to the other, and is conmovement,fandaafrictionakdeyicer cting to onv applyingn'iansiis operative ".Afbrakelicmprising'a rotating nim xe'd supportata rigid arcuate shoe, andfan actuating' device frat ,feachfiendi'fof -"saidi1s`hoe; Seither one: -|of Which-Ideyicesis adapted tofimoife;l the'shoeinto engagementLjwith-I'the;drunione of saidractuatin'g meansA comprisinganz.applying ele'n'ient'gzzanfiiI-I.y termediate member LWhich-J'is pivotal 1y V co`nn'ect'ed with the applying elenientandPis'fconnectedslidy f ably zwith.;the:shoe.=so l'as tofspermit ftheeshoefsto. slide in'-l 'a selectedpl-ane;l t'o'wa'rd's and away lfronithe's: drum-1,2v andai; stop:Whicharrests:thezmove` mentiofgfthezapplyingi'membe' sofa ft yact" anchorage for the1:slioe.i:.

3. In a brake, a shoefapplying devic mp ingi'a housing; aiplungerslidable.thereinranintermediates memberwconectedx:pivotally `:Nvithuthe 25 plungemanrabutmeht zon-the fintermediatetmem. bersiengaging .fsl'idablyivvith4 th corresponding.=;sur; fi face jon theifshoearsaidzi: shoe. surface: lying'xiin ea" direction; nvvhichayvlfi'einattendedpassesa that sidezofvithezidrm iaxisaremotezfromi theizsh'oe; andi 30 means positivelymtconnectingnthe:.eintermediate member-withfthe'sho rasiactallciw aidrelativle "1"- Sliding ,movemen .l

i l thereinglzanei termediatefmemberi.affballzand sofzlietxjointfco'ne. nectingitheintermediate@memberwithfthei:plungi eri ann-abutment `o:151thenintermediatet meiiibeii engaging lidablynwith agilcorrespondingxsrface onzith'esho,e;zasaidafshoersurfaceilyinfg iiiafdirecton' which .when vextendedpasses?to tha ,sideo'fl the' drum axis remote from the shoeandameans p'o'si 53 tively f-connectin'giz-thef; intermediate member .with

termedia-temenber f corxnectedpivotallyfwithhe plungery an?.fabutnientfgonttheintrniediatei meme"` ben'ifengaging'eslidablywitliaacorrespondingsu -2 faced-on Ithefshoesaidshoeasuriaceilyingima, ,t reotionfwvhio 'ewhen;extendednpasses tnfzatlieifsiie` oiithefiirumiagisemotefrofmtheshoe; pin' and slot:connection.oiningtnazintermediat member. tozethe fsloefsoiasl toznerm-itatharfelativgslidngf sisiz' saidyrelativeslidingemoyementif e n the shoe-@Seiden which when extended pa drum .gaxistineindte connentiom aibrake,naiishoe-applningdeviocompr 4tklslliign151eplimaeniilidablieetherleixieznna termediate member,y a .substantially spherical head formed onv said intermediate member, a socket formed in the plunger and'containing the '15 head to allow universal movement of the inter.- mediate member, an abutment on the intermediate member engaging slidably with a corresponding surface on the shoe, said shoe surface lying in a direction which when extended passes to that side of the drum axis remote from the shoe, and means positively connecting the intermediate member with the shoe so as to allow the said relative sliding movement. Y.

8. A brake comprising a rotating drum, a iixed support, a pair of actuating devices at' opposite parts of the support, a pairl of rigid arcuate shoes arranged between the actuating devices so as to be moved thereby into contact with the drum, each of said actuating devices comprising a housing, a pair of plungers mounted slidably therein, an intermediate member interposed between a shoe end and the corresponding plunger, a pivotal connection between the intermediate member and the plunger, and a sliding joint between the intermediate member and the shoe, the sliding being such thatit is directed to that side of the drum axis remote from the shoe in question, and a stop for each plunger in the corresponding housing enabling the said plunger to act as an abutment for its shoe.

9. A brake comprising a rotating drum, a' xed support.. a pair of actuating devices at opposite parts oi' the support, a pair of rigid arcuate shoes arranged between the actuating devices so as to be moved thereby into contact with the drum, eachof said actuating devices comprising a housing, a pair of plungers mounted slidably therein, an intermediate member interposed between the shoe end' and the corresponding plunger, a pivotal connection between the intermediate member and the plunger, a ledge formed in the intermediate member and engaged slidably by the shoe end, a

pin and slot connection holding the intermediatev member upon the shoe so as to permit the 'shoe to slide upon the intermediate member with its end abutting against the wall of the ledge, and a stop for each plunger in the corresponding housing enabling the said plunger tot act as an abutment for its shoe.

10. A brake comprising a rotating drum, a xed support, a pair of actuating devices at opposite parts of the support, a pair. of rigid arcuate shoes arranged between the actuating devicesso as to be moved thereby into contact with the drum,

. each of said actuating devices comprising a housing, a pair of plungers mounted'slidably therein, an intermediate member interposed between a shoe end in the corresponding plunger, a pivota1- connection between the intermediate member and the plunger, a ledge formed in the intermediate member and engaged slidably by theshoe end, a pin andslot connection holding the intermediate member upon the shoe so as to permit the shoe to slide upon the intermediate member with its end abutting against the wall of thef ledge, means for frictionally gripping the shoe and intermediate member together so that normal applying movement of the shoe takes place about the pivot of the intermediate member, andl a stop for each plunger in the corresponding housing enabling the said plunger `to act asan abutment for its shoe.

11. A brake comprising a rotating drum, a iixed support, a pair of rigid arcuate brake shoes, an actuating device arranged to spread apart adjacent ends of said shoes into engagement with the drum, an anchorage between the other ends of said shoes and engaged directly by' one thereof, a hydrauli motor cylinder interposed between the anchorage and the end of the other shoe, hydrauiic means which operate the actuating device and are connected with the motor cylinder so that both are fed in commonl and an intermediate member which is interposed between the opposite end of said other shoe and the actuating device, said intermediate member being connected pivotally with the actuating device and being coupled with the said other shoe so as to allow the latter to slide towards and away from the drum. I

12. A brake comprising a rotating drum, Aa xed support, a pair of rigid arcuate brake shoes, an actuating device arranged to spread apart adjacent ends of said shoes into engagement with the drum, an anchorage between the other ends of said shoes and engaged directly by one thereof, a hydraulic motor cylinder interposed between the anchorage and the end of the other shoe, hydraulic means which operate the actuating vdevice and are connected with the motor cylinder so lthat both are fed in common, and an intermediate member which is interposed between the opposite end of the said other shoe and the actuating device, said intermediate member being connected with the actuating device by a pivotal joint, and having a surface which is engaged slidably by the end of the shoe so that the latter is enabled te slide towards and away from the drum, said surface being so inclined that if extended it passes to that side of the drum centre remote from the shoe in question.

13. A brake comprising a rotating drum, a iixed support, a pair of rigid arcuate brake shoes, an actuating device arranged to spread apart adjacent ends of said shoes into engagement with the drum, an anchorage between the other ends of said shoes and engaged directly by one thereof, a hydraulic motor cylinder interposed between the anchorage and the end of the other shoe, hydraulic means which operate the actuating device and are connected with the motor cylinder so that both arev fed in common, a thrust-transmitting connection in the motor cylinder adapted to provide a wholly mechanical thrust connection between the anchorage and the said other shoe when the motor cylinder loccupies its minimum length, and an intermediate member which is interposed between'the opposite end of the said other shoe and the actuating device, said intermediate member being connected pivotally with the actuating device and being coupled with the said other shoe so as to allow the latter to slide towards and away from the drum.

14. A brake as claimed in claim 11'in which the anchorage comprises a body attached to the fixed support, an adjusting screw mounted in said body, a plunger slidable in the body under operative connection with the brake shoes and i are moved apart as the the screw. l

' 15. A brake comprising a rotating drum, a fixed support, a braking element for cooperation with the drum, means for actuating one end of the element, mounting means for the other end plunger is advanced by Aof the braking element, said mounting means comprising a member `pivotally mounted on the support at a point spaced from the end of the element and capable of transmitting for'ce in compression, a connection between the pivotally mounted member and the braking element including abutting planesurfaces capable of slidduring brake application, and means carried solely by the element and member for positively maintaining the surfaces in cooperative relation and for also establishing a friction resistance to their relative movement in the selected plane Y mitting their relative movement in the selected 16. A brake comprising a rotating drum, a xed support, a braking element for cooperation with the drum, means for actuating one end of the element, mounting means for the other end of the braking element, said mounting means comprising a member pivotally mounted on the support at a point spaced from the end ofthe element and having a portion overlapping said end, said member and braking element being provided with cooperating plane surfaces in abutting relation and capable of relative movement to permit the end of the element to move in a selected plane toward the drum during brake application, and cooperating means between the element and the overlapping portion of the member for positively maintaining the plane surfaces in cooperative position with each other yet perplane.

17. A brake comprising a rotating drum, a fixed support,. a braking element for cooperation with the drum, means for actuating one end of the element, mounting means for the other end of the braking element, said mounting means comprising a member pivotally mounted on the support at a point spaced from the end of the element and having a portion overlapping said end, said member and braking element being provided with cooperating plane surfaces in abutting relation and capable of relative movement t0 permit the end of the element to move in a selected plane toward the drum during brake application, and a pin and slot connection between the element and the member for maintaining the Aplane surfaces in engagement with each other.

18. A brake comprising a rotatable drum, a xed support, a rigid braking element extending over substantially 180 degrees of the drum for cooperation therewith. means carried by the support and positioned adjacent 'one end of the element for actuating said element, and mounting means for the other end of the braking ele- -ment', saidv mounting means comprising amemyber pivotally mounted on the support andv capable of transmitting force in compression, said member and the said mounted end of the braking element being provided with abutting plane surfaces which are so related with respect to the drum that the braking element can move in a selected plane toward the drum during brake application without a wedging action, means for 'preventing disengagement of the abutting surfaces by a relative lateral movement between the pivoted member and the braking element, and spring means for establishing a frictional resistance to movement of the braking element relative to the pivoted member inthe selected plane.

KEITH ERIC LAPWOOD. 

